Dataset: Sterols and Artemia growth

Phytosterols were synthesized by J. Giner. Rhodomonas cultures were labeled by dissolving sterols in 100% ethanol at a concentration of 2 mg/ml, and then adding the sterol solution at a concentration of 20 µl sterol solution per 100 ml stock culture (at stock density 1x106 cells/liter). The cultures were mixed on a LabGenius orbital shaker for 2 hr at 100 rpm to allow the sterols to bind to the algal surfaces. In vivo chlorophyll a was monitored with a Turner handheld fluorometer to ensure that all food was consumed before the subsequent feeding. This avoided the problem of algal growth diluting the phytosterol concentration over time.

Artemia were hatched in an aerated 2L beaker and the nauplii distributed to 4L beakers containing seawater at 32 ppt. Animals were fed daily with Rhodomonas supplemented with phytosterols at 50,000 cells/ml in 3 replicate, aerated containers for 8 days. In vivo fluorescence was measured with a Turner handheld fluorometer to ensure that the Rhodomonas was consumed between feedings. At the end of the experiment the containers were drained, cleaned of debris, and the number of individuals counted. Samples were then strained on 75µm Nitex and transferred to a preweighed 2.5 cm glass-fiber filter. Filters were dried in a 60 degree C oven overnight and weighed on a Mettler analytical balance. A total of 4 experiments were conducted with Artemia, using 3 replicate treatments of 6 phytosterols, except the last experiment when 5 phytosterols were tested. In the first 3 experiments supplementation was begun 2 days after hatching, while in the fourth experiment supplementation was delayed 2 additional days so that animals began supplementation at a larger size. Results were expressed as both average dry weight per individual and total biomass (mg dry wt) per tank.